Various forms of modern wireless communications systems are well known. For example, cellular wireless voice services are now widely deployed in industrialized nations, and technology improvements are expected to enhance and expand cellular wireless services and lead to further deployment.
Accompanying the increased deployment of wireless voice services is an increased demand for wireless data services, such as web-browsing, email and the like. The demand for both types of services reflects the well-identified trend towards the convergence of traditional voice and data services. In particular, wireless local loop (WLL) systems are expected to become a viable alternative to the wired local loop telephone services offered by the existing local telephone companies throughout North America. However, in order to effectively compete with the existing local telephone companies, it is expected that WLL systems will need to provide both toil-quality voice services and high-speed data services.
Both mobile and WLL wireless services will have to provide any voice and data services within prescribed power budgets, as known to those of skill in the art. For example, power-control features are usually incorporated into wireless base stations to ensure that services are offered within government prescribed power budgets.
Various power management techniques are known. In IS-95, for example, it is known to rely on certain characteristics of voice telephone calls to assist in managing power output. Specifically, it is known that during a typical two-way voice telephone call over a wireless voice channel, each party will only speak, on average, for about one-half of the time that the channel is open (“Fifty-percent duty cycle”). This fifty-percent duty cycle can be used on the downlink (i.e. from the base station to the subscriber station), to reduce the amount of power allocated to the voice channels, and thus help keep the power output from the base station within the government-prescribed power budget. However, since the fifty-percent duty cycle is merely an average level of power consumption, over any given time-period the actual power consumed on a voice channel can exceed fifty-percent, thus requiring the allocation of additional power to voice channels in order to accommodate peak power usages.
Keeping the power output within the government-prescribed power budget in a combined voice and data system presents different challenges. In such systems, it is known to allocate a fixed level of power to the voice channels in substantially the same manner as described in the previous paragraph, i.e. the allocation to the voice services is based, at least in part, on the fifty-percent duty cycle. The remainder of the power budget is then allocated to the data channels. On the whole, these power allocations remain fixed for a given base station. However, this method leads to the disadvantage that, when the actual amount of voice traffic over a given time period requires less than the level of allocated power, then the remaining power is wasted.